Wow dude, you sure have ambition for someone using a mouse! I mean the scope of some of these, geez.
If you want to get the most out of your mouse, I recommend using the Pen tool, and using Vector lines. The standard shortcut is "P" in Photoshop. I recommend looking up tutorials if you haven't used it before, as it SEEMS counter intuitive at first. To get you started, maybe look at ctlr + paint http://www.ctrlpaint.com/videos/making-selections-with-the-pen-tool-part-1
He doesn't use it for drawing directly, but i've seen some insane illustrations made with that thing.
Another alternative is to scan your traditional sketches and work on them in Photoshop after the fact. I used to do this before I got a tablet, and had some success.
But geez dude, Raven Enlight? That probably took hella amount of time.